My U.S. patent application Ser. No. 07/830,362, filed Jan. 31, 1992, discloses an apparatus for selective use either in operative association with an existing conventional valve stem or, alternatively, by being attached to a tire rim as a replacement for a conventional valve stem.
A number of other devices are known in the prior art which function as both tire valves and pressure gauges. Representative apparatus of this type are disclosed in the following U.S. Pat. No. 3,230,968, issued Jan. 25, 1966, U.S. Pat. No. 1,517,484, issued Dec. 2, 1924, U.S. Pat. No. 1,671,123, issued May 29, 1928, U.S. Pat. No. 4,606,391, Aug. 19, 1986, U.S. Pat. No. 3,720,224, issued Mar. 13, 1973, and U.S. Pat. No. 4,193,295, issued Mar. 18, 1980.
Combination tire valve and pressure indicator devices are typically characterized by their relative complexity and high expense.